Given that Harry Potter had been using the Room of Requirement for DA meetings in the 5th book and was aware that it would supply you with what you really needed (within the limits of what was possible with transfiguration), why didn't he use it to get a means of contacting Sirius Black that Umbridge wouldn't have been able to monitor (such as an unmonitored fire connected to the Floo Network)?

Perhaps more surprising (given that Harry was apparently near-panic at that point) was the fact that Hermione didn't think of it either, in spite of her otherwise level-headed behavior in that circumstance. Why didn't she think of it either?

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    Honestly, if Sirius had informed him that it was a two way mirror when he gave him the mysteriously wrapped package, it would have been more helpful
    – Mikasa
    Commented Oct 8, 2017 at 2:48
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    How does the Floo network even work? Does someone from the ministry have to add it manually? In that case you couldn't just generate a fireplace and have it be connected. Commented Oct 8, 2017 at 8:45
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    Have you not realised that Harry is actually kind of an idiot? Commented Oct 8, 2017 at 11:15
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    @MikasaPinata If Sirius had informed Harry that it was a two-way mirror, the whole plot of OotP, which is based on lack of information and reliable communication, would have been ruined.
    – svavil
    Commented Oct 8, 2017 at 16:44
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    Is there any proof that the Room of Requirement would have been able to provide a secure means of contacting Sirius? When you're panicking about someone you love being tortured and murdered seems like a bad time to try something purely speculative that you have no idea will work. Commented Oct 9, 2017 at 5:07

4 Answers 4


Harry simply wasn't thinking straight or logically.

Harry was acting erratically and impulsively when he thought Sirius was in danger because of the visions the Dark Lord was giving him. He didn't see anything about that situation clearly because his judgment was clouded by his emotions. He also didn't think of using the two-way mirror Sirius gave him, even though Sirius at the time had specifically told him that it was something he could use if he needed him.

“What is it?’ Harry asked.

‘A way of letting me know if Snape’s giving you a hard time. No, don’t open it in here!’ said Sirius, with a wary look at Mrs Weasley, who was trying to persuade the twins to wear hand-knitted mittens. ‘I doubt Molly would approve – but I want you to use it if you need me, all right?’

‘OK,’ said Harry, stowing the package away in the inside pocket of his jacket, but he knew he would never use whatever it was. It would not be he, Harry, who lured Sirius from his place of safety, no matter how foully Snape treated him in their forthcoming Occlumency classes.”
- Harry Potter and the Order of the Phoenix, Chapter 24 (Occlumency)

Obviously, circumstances had changed since he decided that he wouldn't use the mirror - at the time he was sure that Sirius was already unsafe.

Hermione was handling shouting irrational Harry, she mightn't have time for lateral thinking.

Hermione was trying desperately to convince Harry not to just run off to the Ministry looking for Sirius, which is what he wanted to do. Once she got him to agree to try to contact Sirius first, she had to quickly think of a way to do it - Harry already wanted to just go to the Ministry and was already impatient and angry. It's likely that using the fireplace was the first form of communication she could think of, and at that point she didn't really have time to consider all of her options. She went right from convincing Harry to check on Sirius first to making a plan to do it.

“Sirius is being tortured NOW!’ shouted Harry. ‘We haven’t got time to waste.’

‘But if this is a trick of Voldemort’s, Harry, we’ve got to check, we’ve got to.’

‘How?’ Harry demanded. ‘How’re we going to check?’

‘We’ll have to use Umbridge’s fire and see if we can contact him,’ said Hermione, who looked positively terrified at the thought.”
- Harry Potter and the Order of the Phoenix, Chapter 32 (Out of the Fire)

In addition, Hermione knew Harry had used the fireplace to contact Sirius before, and so it was likely the first thing she thought of when trying to figure out how to contact him. It would likely be a lot easier for her to quickly think of something they'd used already than the indirect way of using the Room of Requirement, especially while trying to keep Harry from making reckless decisions.

  • This holds for the second time that Harry tries to contract Sirius but what about the first time? They weren't in a hurry on that occasion. Commented Oct 8, 2017 at 15:48
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    @TheDarkLord, also, on that first occasion, why didn't Sirius ask Harry why he wasn't using the mirror? I rather suspect that out-of-universe the mirror was added as an afterthought, because it was going to be needed later, and neither JKR nor the editors caught the fact that it introduced a plot hole. Commented Oct 9, 2017 at 0:48
  • @HarryJohnston Yeah, I know. Commented Oct 9, 2017 at 7:46
  • also what about the mirror that Sirius gave him
    – HN17
    Commented Oct 13, 2017 at 7:29
  • Sirius wasn't real clear on what it was. "‘A way of letting me know if Snape’s giving you a hard time." and "‘I doubt Molly would approve" To me that sounds more like magical signal flare than cell phone. It wasn't until after Sirius' death that he read the note about what it was. Would Hermione have known about the mirror to suggest it at that time? I don't remember Harry telling her about it.
    – stonemetal
    Commented Nov 8, 2022 at 8:30

The Room of Requirement had already been found when the DA was discovered so it would either be locked, guarded or otherwise tampered with to prevent students from using it.

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    Umbridge wasn't a particularly talented witch, and couldn't even get into the Headmaster's office. I have serious doubts that the Room of Requirement would have been "locked" or "otherwise tampered with", but it's possible that it was guarded. However, if they can secure time in Umbridge's office (where she spends most of her time), they can also secure time in the Room of Requirement. Commented Oct 9, 2017 at 14:04

It is one of the implicit limitations of magic in the Harry Potter universe:

The room of requirements is never used by Rowling to create magical objects. It created a bathroom when Ron wanted one. It did not create or fix Malfoy's vanishing cabinet. It does not create wands. This is probably one of the five exceptions to Gamp's Law of Elemental Transfiguration (only food is explicitly mentioned in the books).

If the room of requirements created magical objects, it would be famous instead of obscure. It would solve every problem that could exist in this (already) magical world.

  • Good point - now that I think about it, there aren't any examples in the book of the Room making magical objects. Commented Oct 9, 2017 at 14:39

It's not really an obvious choice, and it might not be a good choice, as a spell to monitor all floo fireplaces might've also affected the room of requirement, as there's always stronger magic, making the room risky. If you have a network, such as the floo network, you can tell where someone's coming from, and where they're going, and Umbridge might've rigged to monitor all floo in, say, a 20 mile radius, and the room of requirement can't apparate, only transfigurate. This all doesn't rule out an oversight on the author's part, or that neither of them was really thinking straight about the room.

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